static void mmc_panic_notify_remove(struct hd_struct *hd)
{
struct device *dev = part_to_dev(hd);
drv_ctx.hd = NULL;
pr_info(KERN_INFO "apanic: Unbound from %s\n", dev_name(dev));
}
struct hd_struct *get_part(char *name)
{
dev_t devt;
int partno;
struct disk_part_iter piter;
struct gendisk *disk;
struct hd_struct *part = NULL;
if (!name)
return part;
devt = blk_lookup_devt("mmcblk0", 0);
disk = get_gendisk(devt, &partno);
if (!disk || get_capacity(disk) == 0)
return 0;
disk_part_iter_init(&piter, disk, 0);
while ((part = disk_part_iter_next(&piter))) {
if (part->info && !strcmp(part->info->volname, name)) {
get_device(part_to_dev(part));
break;
}
}
disk_part_iter_exit(&piter);
return part;
}
static void mmc_memdump_notify_remove(struct hd_struct *hd)
{
struct device *dev = part_to_dev(hd);
memdump_ctx.hd = NULL;
pr_info("apanic: Unbound from memdump backing dev" " %s\n",
dev_name(dev));
}
static void delete_partition_rcu_cb(struct rcu_head *head)
{
struct hd_struct *part = container_of(head, struct hd_struct, rcu_head);
part->start_sect = 0;
part->nr_sects = 0;
part_stat_set_all(part, 0);
put_device(part_to_dev(part));
}
/**
* devt_from_partuuid - looks up the dev_t of a partition by its UUID
* @uuid: min 36 byte char array containing a hex ascii UUID
*
* The function will return the first partition which contains a matching
* UUID value in its partition_meta_info struct. This does not search
* by filesystem UUIDs.
*
* If @uuid is followed by a "/PARTNROFF=%d", then the number will be
* extracted and used as an offset from the partition identified by the UUID.
*
* Returns the matching dev_t on success or 0 on failure.
*/
static dev_t devt_from_partuuid(char *uuid_str)
{
dev_t res = 0;
struct device *dev = NULL;
u8 uuid[16];
struct gendisk *disk;
struct hd_struct *part;
int offset = 0;
if (strlen(uuid_str) < 36)
goto done;
/* Check for optional partition number offset attributes. */
if (uuid_str[36]) {
char c = 0;
/* Explicitly fail on poor PARTUUID syntax. */
if (sscanf(&uuid_str[36],
"/PARTNROFF=%d%c", &offset, &c) != 1) {
printk(KERN_ERR "VFS: PARTUUID= is invalid.\n"
"Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
if (root_wait)
printk(KERN_ERR
"Disabling rootwait; root= is invalid.\n");
root_wait = 0;
goto done;
}
}
/* Pack the requested UUID in the expected format. */
part_pack_uuid(uuid_str, uuid);
dev = class_find_device(&block_class, NULL, uuid, &match_dev_by_uuid);
if (!dev)
goto done;
res = dev->devt;
/* Attempt to find the partition by offset. */
if (!offset)
goto no_offset;
res = 0;
disk = part_to_disk(dev_to_part(dev));
part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
if (part) {
res = part_devt(part);
put_device(part_to_dev(part));
}
no_offset:
put_device(dev);
done:
return res;
}
static void mmc_memdump_notify_add(struct hd_struct *hd)
{
struct device *dev = part_to_dev(hd);
/* no need to disturb the backing device now */
memdump_ctx.hd = hd;
pr_err("apanic: memdump backing device set to '%s(%u:%u)'\n",
dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
return;
}
struct hd_struct *add_partition(struct gendisk *disk, int partno,
sector_t start, sector_t len, int flags,
struct partition_meta_info *info)
{
struct hd_struct *p;
dev_t devt = MKDEV(0, 0);
struct device *ddev = disk_to_dev(disk);
struct device *pdev;
struct disk_part_tbl *ptbl;
const char *dname;
int err;
err = disk_expand_part_tbl(disk, partno);
if (err)
return ERR_PTR(err);
ptbl = disk->part_tbl;
if (ptbl->part[partno])
return ERR_PTR(-EBUSY);
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return ERR_PTR(-EBUSY);
if (!init_part_stats(p)) {
err = -ENOMEM;
goto out_free;
}
seqcount_init(&p->nr_sects_seq);
pdev = part_to_dev(p);
p->start_sect = start;
p->alignment_offset =
queue_limit_alignment_offset(&disk->queue->limits, start);
p->discard_alignment =
queue_limit_discard_alignment(&disk->queue->limits, start);
p->nr_sects = len;
p->partno = partno;
p->policy = get_disk_ro(disk);
if (info) {
struct partition_meta_info *pinfo = alloc_part_info(disk);
if (!pinfo)
goto out_free_stats;
memcpy(pinfo, info, sizeof(*info));
p->info = pinfo;
}
dname = dev_name(ddev);
if (isdigit(dname[strlen(dname) - 1]
static void mmc_panic_erase(void)
{
int i = 0;
struct apanic_data *ctx = &drv_ctx;
struct block_device *bdev;
struct bio bio;
struct bio_vec bio_vec;
struct completion complete;
struct page *page;
struct device *dev = part_to_dev(drv_ctx.hd);
if (!ctx->hd || !ctx->mmc_panic_ops)
goto out_err;
bdev = blkdev_get_by_dev(dev->devt, FMODE_WRITE, NULL);
if (IS_ERR(bdev)) {
pr_err("apanic: open device failed with %ld\n", PTR_ERR(bdev));
goto out_err;
}
page = virt_to_page(ctx->bounce);
memset(ctx->bounce, 0, PAGE_SIZE);
while (i < ctx->hd->nr_sects) {
bio_init(&bio);
bio.bi_io_vec = &bio_vec;
bio_vec.bv_offset = 0;
bio_vec.bv_page = page;
bio.bi_vcnt = 1;
bio.bi_idx = 0;
bio.bi_sector = i;
if (ctx->hd->nr_sects - i >= 8) {
bio_vec.bv_len = PAGE_SIZE;
bio.bi_size = PAGE_SIZE;
i += 8;
} else {
bio_vec.bv_len = (ctx->hd->nr_sects - i) * 512;
bio.bi_size = (ctx->hd->nr_sects - i) * 512;
i = ctx->hd->nr_sects;
}
bio.bi_bdev = bdev;
init_completion(&complete);
bio.bi_private = &complete;
bio.bi_end_io = mmc_bio_complete;
submit_bio(WRITE, &bio);
wait_for_completion(&complete);
}
blkdev_put(bdev, FMODE_WRITE);
out_err:
return;
}
/**
* disk_part_iter_next - proceed iterator to the next partition and return it
* @piter: iterator of interest
*
* Proceed @piter to the next partition and return it.
*
* CONTEXT:
* Don't care.
*/
struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
{
struct disk_part_tbl *ptbl;
int inc, end;
/* put the last partition */
disk_put_part(piter->part);
piter->part = NULL;
/* get part_tbl */
rcu_read_lock();
ptbl = rcu_dereference(piter->disk->part_tbl);
/* determine iteration parameters */
if (piter->flags & DISK_PITER_REVERSE) {
inc = -1;
if (piter->flags & (DISK_PITER_INCL_PART0 |
DISK_PITER_INCL_EMPTY_PART0))
end = -1;
else
end = 0;
} else {
inc = 1;
end = ptbl->len;
}
/* iterate to the next partition */
for (; piter->idx != end; piter->idx += inc) {
struct hd_struct *part;
part = rcu_dereference(ptbl->part[piter->idx]);
if (!part)
continue;
if (!part->nr_sects &&
!(piter->flags & DISK_PITER_INCL_EMPTY) &&
!(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
piter->idx == 0))
continue;
get_device(part_to_dev(part));
piter->part = part;
piter->idx += inc;
break;
}
rcu_read_unlock();
return piter->part;
}
void delete_partition(struct gendisk *disk, int partno)
{
struct disk_part_tbl *ptbl = disk->part_tbl;
struct hd_struct *part;
if (partno >= ptbl->len)
return;
part = ptbl->part[partno];
if (!part)
return;
rcu_assign_pointer(ptbl->part[partno], NULL);
rcu_assign_pointer(ptbl->last_lookup, NULL);
kobject_put(part->holder_dir);
device_del(part_to_dev(part));
hd_struct_kill(part);
}
/**
* disk_get_part - get partition
* @disk: disk to look partition from
* @partno: partition number
*
* Look for partition @partno from @disk. If found, increment
* reference count and return it.
*
* CONTEXT:
* Don't care.
*
* RETURNS:
* Pointer to the found partition on success, NULL if not found.
*/
struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
{
struct hd_struct *part = NULL;
struct disk_part_tbl *ptbl;
if (unlikely(partno < 0))
return NULL;
rcu_read_lock();
ptbl = rcu_dereference(disk->part_tbl);
if (likely(partno < ptbl->len)) {
part = rcu_dereference(ptbl->part[partno]);
if (part)
get_device(part_to_dev(part));
}
rcu_read_unlock();
return part;
}
int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmd, unsigned int flags, get_block_t get_block,
dax_iodone_t complete_unwritten)
{
struct file *file = vma->vm_file;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct buffer_head bh;
unsigned blkbits = inode->i_blkbits;
unsigned long pmd_addr = address & PMD_MASK;
bool write = flags & FAULT_FLAG_WRITE;
struct block_device *bdev;
pgoff_t size, pgoff;
sector_t block;
int error, result = 0;
bool alloc = false;
/* dax pmd mappings require pfn_t_devmap() */
if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
return VM_FAULT_FALLBACK;
/* Fall back to PTEs if we're going to COW */
if (write && !(vma->vm_flags & VM_SHARED)) {
split_huge_pmd(vma, pmd, address);
dax_pmd_dbg(NULL, address, "cow write");
return VM_FAULT_FALLBACK;
}
/* If the PMD would extend outside the VMA */
if (pmd_addr < vma->vm_start) {
dax_pmd_dbg(NULL, address, "vma start unaligned");
return VM_FAULT_FALLBACK;
}
if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
dax_pmd_dbg(NULL, address, "vma end unaligned");
return VM_FAULT_FALLBACK;
}
pgoff = linear_page_index(vma, pmd_addr);
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (pgoff >= size)
return VM_FAULT_SIGBUS;
/* If the PMD would cover blocks out of the file */
if ((pgoff | PG_PMD_COLOUR) >= size) {
dax_pmd_dbg(NULL, address,
"offset + huge page size > file size");
return VM_FAULT_FALLBACK;
}
memset(&bh, 0, sizeof(bh));
bh.b_bdev = inode->i_sb->s_bdev;
block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
bh.b_size = PMD_SIZE;
if (get_block(inode, block, &bh, 0) != 0)
return VM_FAULT_SIGBUS;
if (!buffer_mapped(&bh) && write) {
if (get_block(inode, block, &bh, 1) != 0)
return VM_FAULT_SIGBUS;
alloc = true;
}
bdev = bh.b_bdev;
/*
* If the filesystem isn't willing to tell us the length of a hole,
* just fall back to PTEs. Calling get_block 512 times in a loop
* would be silly.
*/
if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
dax_pmd_dbg(&bh, address, "allocated block too small");
return VM_FAULT_FALLBACK;
}
/*
* If we allocated new storage, make sure no process has any
* zero pages covering this hole
*/
if (alloc) {
loff_t lstart = pgoff << PAGE_SHIFT;
loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */
truncate_pagecache_range(inode, lstart, lend);
}
i_mmap_lock_read(mapping);
/*
* If a truncate happened while we were allocating blocks, we may
* leave blocks allocated to the file that are beyond EOF. We can't
* take i_mutex here, so just leave them hanging; they'll be freed
* when the file is deleted.
*/
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (pgoff >= size) {
result = VM_FAULT_SIGBUS;
goto out;
}
if ((pgoff | PG_PMD_COLOUR) >= size) {
dax_pmd_dbg(&bh, address,
"offset + huge page size > file size");
goto fallback;
}
if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
spinlock_t *ptl;
pmd_t entry;
struct page *zero_page = get_huge_zero_page();
if (unlikely(!zero_page)) {
dax_pmd_dbg(&bh, address, "no zero page");
goto fallback;
}
ptl = pmd_lock(vma->vm_mm, pmd);
if (!pmd_none(*pmd)) {
spin_unlock(ptl);
dax_pmd_dbg(&bh, address, "pmd already present");
goto fallback;
}
dev_dbg(part_to_dev(bdev->bd_part),
"%s: %s addr: %lx pfn: <zero> sect: %llx\n",
__func__, current->comm, address,
(unsigned long long) to_sector(&bh, inode));
entry = mk_pmd(zero_page, vma->vm_page_prot);
entry = pmd_mkhuge(entry);
set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry);
result = VM_FAULT_NOPAGE;
spin_unlock(ptl);
} else {
struct blk_dax_ctl dax = {
.sector = to_sector(&bh, inode),
.size = PMD_SIZE,
};
long length = dax_map_atomic(bdev, &dax);
if (length < 0) {
result = VM_FAULT_SIGBUS;
goto out;
}
if (length < PMD_SIZE) {
dax_pmd_dbg(&bh, address, "dax-length too small");
dax_unmap_atomic(bdev, &dax);
goto fallback;
}
if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
dax_pmd_dbg(&bh, address, "pfn unaligned");
dax_unmap_atomic(bdev, &dax);
goto fallback;
}
if (!pfn_t_devmap(dax.pfn)) {
dax_unmap_atomic(bdev, &dax);
dax_pmd_dbg(&bh, address, "pfn not in memmap");
goto fallback;
}
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
clear_pmem(dax.addr, PMD_SIZE);
wmb_pmem();
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
result |= VM_FAULT_MAJOR;
}
dax_unmap_atomic(bdev, &dax);
/*
* For PTE faults we insert a radix tree entry for reads, and
* leave it clean. Then on the first write we dirty the radix
* tree entry via the dax_pfn_mkwrite() path. This sequence
* allows the dax_pfn_mkwrite() call to be simpler and avoid a
* call into get_block() to translate the pgoff to a sector in
* order to be able to create a new radix tree entry.
*
* The PMD path doesn't have an equivalent to
* dax_pfn_mkwrite(), though, so for a read followed by a
* write we traverse all the way through __dax_pmd_fault()
* twice. This means we can just skip inserting a radix tree
* entry completely on the initial read and just wait until
* the write to insert a dirty entry.
*/
if (write) {
error = dax_radix_entry(mapping, pgoff, dax.sector,
true, true);
if (error) {
dax_pmd_dbg(&bh, address,
"PMD radix insertion failed");
goto fallback;
}
}
dev_dbg(part_to_dev(bdev->bd_part),
"%s: %s addr: %lx pfn: %lx sect: %llx\n",
__func__, current->comm, address,
pfn_t_to_pfn(dax.pfn),
(unsigned long long) dax.sector);
result |= vmf_insert_pfn_pmd(vma, address, pmd,
dax.pfn, write);
}
out:
i_mmap_unlock_read(mapping);
if (buffer_unwritten(&bh))
complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
return result;
fallback:
count_vm_event(THP_FAULT_FALLBACK);
result = VM_FAULT_FALLBACK;
goto out;
}
EXPORT_SYMBOL_GPL(__dax_pmd_fault);
/**
* dax_pmd_fault - handle a PMD fault on a DAX file
* @vma: The virtual memory area where the fault occurred
* @vmf: The description of the fault
* @get_block: The filesystem method used to translate file offsets to blocks
*
* When a page fault occurs, filesystems may call this helper in their
* pmd_fault handler for DAX files.
*/
int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmd, unsigned int flags, get_block_t get_block,
dax_iodone_t complete_unwritten)
{
int result;
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
if (flags & FAULT_FLAG_WRITE) {
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
}
result = __dax_pmd_fault(vma, address, pmd, flags, get_block,
complete_unwritten);
if (flags & FAULT_FLAG_WRITE)
sb_end_pagefault(sb);
return result;
}
static void mmc_panic_notify_add(struct hd_struct *hd)
{
struct apanic_data *ctx = &drv_ctx;
struct panic_header *hdr = ctx->bounce;
struct block_device *bdev;
struct bio bio;
struct bio_vec bio_vec;
struct completion complete;
struct page *page;
struct device *dev = part_to_dev(hd);
if (!ctx->mmc_panic_ops) {
pr_err("apanic: found apanic partition, but apanic not "
"initialized\n");
return;
}
bdev = blkdev_get_by_dev(dev->devt, FMODE_WRITE, NULL);
if (IS_ERR(bdev)) {
pr_err("apanic: open device failed with %ld\n",
PTR_ERR(bdev));
goto out;
}
ctx->hd = hd;
page = virt_to_page(ctx->bounce);
bio_init(&bio);
bio.bi_io_vec = &bio_vec;
bio_vec.bv_page = page;
bio_vec.bv_len = PAGE_SIZE;
bio_vec.bv_offset = 0;
bio.bi_vcnt = 1;
bio.bi_idx = 0;
bio.bi_size = PAGE_SIZE;
bio.bi_bdev = bdev;
bio.bi_sector = 0;
init_completion(&complete);
bio.bi_private = &complete;
bio.bi_end_io = mmc_bio_complete;
submit_bio(READ, &bio);
wait_for_completion(&complete);
blkdev_put(bdev, FMODE_READ);
pr_err("apanic: Bound to mmc block device '%s(%u:%u)'\n",
dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
if (hdr->magic != PANIC_MAGIC) {
pr_info("apanic: No panic data available\n");
goto out;
}
if (hdr->version != PHDR_VERSION) {
pr_info("apanic: Version mismatch (%d != %d)\n",
hdr->version, PHDR_VERSION);
goto out;
}
memcpy(&ctx->curr, hdr, sizeof(struct panic_header));
pr_info("apanic: c(%u, %u) t(%u, %u) a(%u, %u)\n",
hdr->console_offset, hdr->console_length,
hdr->threads_offset, hdr->threads_length,
hdr->app_threads_offset, hdr->app_threads_length);
if (hdr->console_length) {
ctx->apanic_console = create_proc_entry("apanic_console",
S_IFREG | S_IRUGO,
NULL);
if (!ctx->apanic_console)
pr_err("apanic: failed creating procfile\n");
else {
ctx->apanic_console->read_proc =
apanic_proc_read_mmc;
ctx->apanic_console->write_proc =
apanic_proc_write;
ctx->apanic_console->size = hdr->console_length;
ctx->apanic_console->data = (void *) 1;
}
}
if (hdr->threads_length) {
ctx->apanic_threads = create_proc_entry("apanic_threads",
S_IFREG | S_IRUGO,
NULL);
if (!ctx->apanic_threads)
pr_err("apanic: failed creating procfile\n");
else {
ctx->apanic_threads->read_proc =
apanic_proc_read_mmc;
ctx->apanic_threads->write_proc =
apanic_proc_write;
ctx->apanic_threads->size = hdr->threads_length;
ctx->apanic_threads->data = (void *) 2;
}
}
if (hdr->app_threads_length) {
ctx->apanic_app_threads = create_proc_entry(
"apanic_app_threads", S_IFREG | S_IRUGO, NULL);
if (!ctx->apanic_app_threads)
pr_err("%s: failed creating procfile\n", __func__);
else {
ctx->apanic_app_threads->read_proc
= apanic_proc_read_mmc;
ctx->apanic_app_threads->write_proc = apanic_proc_write;
ctx->apanic_app_threads->size = hdr->app_threads_length;
ctx->apanic_app_threads->data = (void *) 3;
}
}
out:
ctx->apanic_annotate = create_proc_entry("apanic_annotate",
S_IFREG | S_IRUGO | S_IWUSR, NULL);
if (!ctx->apanic_annotate)
printk(KERN_ERR "%s: failed creating procfile\n", __func__);
else {
ctx->apanic_annotate->read_proc = apanic_proc_read_annotation;
ctx->apanic_annotate->write_proc = apanic_proc_annotate;
ctx->apanic_annotate->size = 0;
ctx->apanic_annotate->data = NULL;
}
return;
}
static int apanic_proc_read_mmc(char *buffer, char **start, off_t offset,
int count, int *peof, void *dat)
{
int i, index = 0;
int ret;
int start_sect;
int end_sect;
size_t file_length;
off_t file_offset;
struct apanic_data *ctx = &drv_ctx;
struct block_device *bdev;
struct bio bio;
struct bio_vec bio_vec;
struct completion complete;
struct page *page;
struct device *dev = part_to_dev(drv_ctx.hd);
if (!ctx->hd || !ctx->mmc_panic_ops)
return -EBUSY;
if (!count)
return 0;
mutex_lock(&drv_mutex);
switch ((int) dat) {
case 1: /* apanic_console */
file_length = ctx->curr.console_length;
file_offset = ctx->curr.console_offset;
break;
case 2: /* apanic_threads */
file_length = ctx->curr.threads_length;
file_offset = ctx->curr.threads_offset;
break;
case 3: /* apanic_app_threads */
file_length = ctx->curr.app_threads_length;
file_offset = ctx->curr.app_threads_offset;
break;
default:
pr_err("Bad dat (%d)\n", (int) dat);
mutex_unlock(&drv_mutex);
return -EINVAL;
}
if ((offset + count) > file_length) {
mutex_unlock(&drv_mutex);
return 0;
}
bdev = blkdev_get_by_dev(dev->devt, FMODE_READ, NULL);
if (IS_ERR(bdev)) {
pr_err("apanic: open device failed with %ld\n", PTR_ERR(bdev));
ret = PTR_ERR(bdev);
goto out_err;
}
page = virt_to_page(ctx->bounce);
start_sect = (file_offset + offset) / 512;
end_sect = (file_offset + offset + count - 1) / 512;
for (i = start_sect; i <= end_sect; i++) {
bio_init(&bio);
bio.bi_io_vec = &bio_vec;
bio_vec.bv_page = page;
bio_vec.bv_len = 512;
bio_vec.bv_offset = 0;
bio.bi_vcnt = 1;
bio.bi_idx = 0;
bio.bi_size = 512;
bio.bi_bdev = bdev;
bio.bi_sector = i;
init_completion(&complete);
bio.bi_private = &complete;
bio.bi_end_io = mmc_bio_complete;
submit_bio(READ, &bio);
wait_for_completion(&complete);
if (!test_bit(BIO_UPTODATE, &bio.bi_flags)) {
ret = -EIO;
goto out_err;
}
if ((i == start_sect)
&& ((file_offset + offset) % 512 != 0)) {
/* first sect, may be the only sect */
memcpy(buffer, ctx->bounce + (file_offset + offset)
% 512, min((unsigned long) count,
(unsigned long)
(512 -
(file_offset + offset) % 512)));
index += min((unsigned long) count, (unsigned long)
(512 - (file_offset + offset) % 512));
} else if ((i == end_sect)
&& ((file_offset + offset + count)
% 512 != 0)) {
/* last sect */
memcpy(buffer + index, ctx->bounce, (file_offset +
offset +
count) % 512);
} else {
/* middle sect */
memcpy(buffer + index, ctx->bounce, 512);
index += 512;
}
}
blkdev_put(bdev, FMODE_READ);
*start = (char *) count;
if ((offset + count) == file_length)
*peof = 1;
mutex_unlock(&drv_mutex);
return count;
out_err:
mutex_unlock(&drv_mutex);
return ret;
}
/**
* devt_from_partuuid - looks up the dev_t of a partition by its UUID
* @uuid: char array containing ascii UUID
*
* The function will return the first partition which contains a matching
* UUID value in its partition_meta_info struct. This does not search
* by filesystem UUIDs.
*
* If @uuid is followed by a "/PARTNROFF=%d", then the number will be
* extracted and used as an offset from the partition identified by the UUID.
*
* Returns the matching dev_t on success or 0 on failure.
*/
static dev_t devt_from_partuuid(const char *uuid_str)
{
dev_t res = 0;
struct uuidcmp cmp;
struct device *dev = NULL;
struct gendisk *disk;
struct hd_struct *part;
int offset = 0;
bool clear_root_wait = false;
char *slash;
cmp.uuid = uuid_str;
slash = strchr(uuid_str, '/');
/* Check for optional partition number offset attributes. */
if (slash) {
char c = 0;
/* Explicitly fail on poor PARTUUID syntax. */
if (sscanf(slash + 1,
"PARTNROFF=%d%c", &offset, &c) != 1) {
clear_root_wait = true;
goto done;
}
cmp.len = slash - uuid_str;
} else {
cmp.len = strlen(uuid_str);
}
if (!cmp.len) {
clear_root_wait = true;
goto done;
}
dev = class_find_device(&block_class, NULL, &cmp,
&match_dev_by_uuid);
if (!dev)
goto done;
res = dev->devt;
/* Attempt to find the partition by offset. */
if (!offset)
goto no_offset;
res = 0;
disk = part_to_disk(dev_to_part(dev));
part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
if (part) {
res = part_devt(part);
put_device(part_to_dev(part));
}
no_offset:
put_device(dev);
done:
if (clear_root_wait) {
pr_err("VFS: PARTUUID= is invalid.\n"
"Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
if (root_wait)
pr_err("Disabling rootwait; root= is invalid.\n");
root_wait = 0;
}
return res;
}
